Enhancing hydrogen evolution of g-C3N4 with nitrogen vacancies by ethanol thermal treatment.

A highly photoactive nitrogen-deficient g-C₃N₄ photocatalyst with porous frame work has been prepared by a simple, effective, and environmental-friendly method of ethanol thermal treatment. It is found that the as-synthesized catalyst exhibits an enhanced visible light photocatalytic activity for H₂ evolution. The H₂-evolution rate on the treated g-C₃N₄ is 4.2 times higher than the untreated-C₃N₄. The treated g-C₃N₄ and untreated g-C₃N₄ are characterized by Fourier transform-infrared spectra (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), UV-Vis absorption (UV-Vis), photocurrent measurement, and electrochemical impedance spectroscopy (EIS). Characterization results show that the ethanol thermal treatment induces nitrogen vacancies and hierarchical porous structure in g-C₃N₄. Such a structural reconstruction is beneficial for improving optical absorption and hindering photoinduced charger recombination on g-C₃N₄, resulting in the enhanced photocatalytic activity. This work would offer a reference route to develop high-performance metal-free photocatalysts.Schematic of the effect on the structure of g-C₃N₄ by the ethanol thermal treatment<graphic></graphic> [ABSTRACT FROM AUTHOR]